Lateral heterogeneity of basin-plain turbidites of the Cloridorme formation, Quebec, Canada: implications for horizontal well prediction

Abstract

Facies models for basin-plain turbidite systems often depict very simplistic event-bed geometries that are tabular at the kilometer scale. However, recent studies have demonstrated more complex facies architectures, including rapid changes in event-bed thickness and facies composition. This lateral event-bed heterogeneity can have a significant impact on reservoir prediction, heterogeneity, and production in hydrocarbon reservoirs developed in basin-plain turbidite systems. Coastal outcrops on the Gaspe Peninsula in Quebec expose the Middle Ordovician Cloridorme Formation, a synorogenic ‘flysch’ turbidite system developed in the Taconic foreland basin. The formation is interpreted to occupy a basin-floor position due to long-distance (10s of kilometers) correlations of bedsets in the direction of current-flow. This outcrop-based study of the Cloridorme Formation was conducted to better understand the detailed turbidite and hybrid-event-bed architecture in a basin-plain setting. High-resolution drone photogrammetry, centimeter-scale measured sections, digital lithology logs, and handheld gamma-ray scintillometry data characterize this turbidite system at event-bed scales. While most beds in this outcrop study can be traced for 600 meters or more, our results indicate significant intra- and inter-bed lateral complexity, including changes in bed thickness, grain size distribution, and sedimentary structures. This study provides a framework for event-bed lateral variability in basin-plain settings, using the Cloridorme Formation and other well-constrained outcrop analogs. The quantification of these lateral changes can be used for the management of subsurface heterogeneity in conventional and unconventional hydrocarbon reservoir systems, through reservoir model parameterization and prediction of heterogeneity in horizontal wells.